Virtual synchronous generator inertia damping adaptive control method

Abstract

The invention provides a virtual synchronous generator inertia damping self-adaptive control method. The method comprises the following steps that 1, parameters are initialized through a VSG control system, and the state of a power grid is collected in real time; 2, according to the evaluation of the state of the power grid, the VSG control system determines whether virtual inertia or a damping coefficient needs to be increased so as to adapt to the dynamic change of the power grid; and step 3, further judging whether parameters need to be adjusted through the VSG control system according to whether the state of the power grid is stable or not. By cooperatively adjusting the rotational inertia and the damping coefficient of the virtual synchronous generator, suppression of the power grid frequency deviation is realized, so that the stability and the dynamic response capability of the system are improved.

Description

Technical Field

[0001] The invention mainly relates to the technical field of automation and electric power industry, and in particular to a virtual synchronous generator inertia damping adaptive control method. Background Art

[0002] With the rapid development of renewable energy generation technology, especially the large-scale grid connection of distributed power sources such as wind power and photovoltaic power generation, the traditional grid structure and operation mode are facing unprecedented challenges. These renewable energy generation systems are usually connected to the grid through inverters. Due to the inherent characteristics of their power electronic equipment, the grid-connected system has low inertia and low damping problems, which may lead to a decrease in system stability when the grid is disturbed.

[0003] To solve this problem, researchers proposed the virtual synchronous generator (VSG) technology, which simulates the operating characteristics of traditional synchronous generators to provide support similar to rotational inertia and damping for the power grid, thereby improving the dynamic response capability of the power grid. The core of VSG technology lies in its control strategy, which can adaptively adjust the inertia damping parameters under different power grid conditions to maintain the stable operation of the power grid.

[0004] In practical applications, the inertia and damping parameters of the VSG need to be dynamically adjusted according to the real-time status of the power grid. This adaptive control method can adjust the control parameters of the VSG in real time according to the frequency, voltage and other signals of the power grid to adapt to the changes in the power grid. For example, when the power grid is disturbed, the VSG can quickly increase its virtual inertia to provide sufficient energy buffering and reduce the fluctuation of the power grid frequency; at the same time, by adjusting the damping parameters, the power oscillation in the power grid can be suppressed, the damping ratio of the system can be improved, and the stability of the power grid can be enhanced.

[0005] In addition, VSG technology can also be combined with energy storage systems to provide additional inertia support and primary frequency regulation capabilities. This combined use can not only improve the stability of the power grid, but also increase the penetration rate of renewable energy generation, allowing the power grid to more effectively accept and utilize renewable energy generation resources. Summary of the invention

[0006] The present invention mainly provides a virtual synchronous generator inertia damping adaptive control method to solve the technical problems raised in the above background technology.

[0007] The technical solution adopted by the present invention to solve the above technical problems is:

[0008] A virtual synchronous generator inertia damping adaptive control method comprises the following steps:

[0009] Step 1: Initialize parameters and collect grid status in real time through the VSG control system;

[0010] Step 2: Based on the evaluation of the grid status, the VSG control system decides whether it is necessary to increase the virtual inertia or damping coefficient to adapt to the dynamic changes of the grid;

[0011] Step 3: The VSG control system further determines whether parameters need to be adjusted based on whether the power grid state is stable;

[0012] In step three, the VSG control system adjusts the virtual inertia or damping coefficient accordingly according to whether the frequency deviation or change rate still exceeds the preset threshold. If the grid state is stable, the system will maintain the current parameters. This adaptive process is cyclic until the system determines that the grid state is stable and no further adjustment is required, at which point the process ends.

[0013] Furthermore, in step 1, the grid status collected in real time by the VSG control system includes frequency deviation and frequency change rate.

[0014] Furthermore, the VSG control system monitors grid parameters in real time, including frequency and voltage, which are the basis for the control system to make adjustment decisions. By identifying the current operating status, the VSG control system can determine whether frequency modulation operations are required and then determine the steady-state values ​​of the virtual inertia and damping coefficient. These parameters are crucial for simulating the response of synchronous generators.

[0015] Furthermore, as the frequency regulation phase is determined, the VSG control system enters an adaptive mode and dynamically adjusts the control parameters of the VSG to respond to the frequency changes of the power grid.

[0016] Furthermore, as the frequency modulation stage is judged, the control system of the VSG enters the adaptive mode, and the process of dynamically adjusting the control parameters of the VSG to respond to the frequency changes of the power grid involves accurate PWM signal generation and dual closed-loop control of voltage and current. It is necessary to ensure that the output of the VSG is consistent with the control target while maintaining voltage stability and power factor correction.

[0017] Furthermore, as the frequency modulation stage is judged, the VSG control system enters the adaptive mode, and the process of dynamically adjusting the control parameters of the VSG to respond to the frequency changes of the power grid is a closed-loop system. After the frequency modulation control is executed, the system will monitor the power grid frequency again to confirm whether further adjustment is needed.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) Collaborative adaptive control: This strategy suppresses the frequency deviation of the power grid by collaboratively adjusting the moment of inertia and damping coefficient of the virtual synchronous generator, thereby improving the stability and dynamic response capability of the system.

[0020] 2) Control model optimization: Based on the traditional VSG control model, an adaptive adjustment mechanism of the moment of inertia and damping coefficient is introduced. By establishing a coordinated adaptive control strategy model, a comparative analysis of the output active power and frequency waveforms under different control modes is carried out.

[0021] 3) Parameter change stability analysis: Through theoretical analysis and simulation verification, a method to ensure system stability under parameter changes is proposed, including the value expressions and trigger conditions of the moment of inertia and damping coefficient.

[0022] 4) Strong adaptability: By real-time monitoring of the grid status and dynamically adjusting control parameters, the strategy can adapt to different grid conditions and operating requirements, and improve the grid's ability to accept renewable energy.

[0023] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The process of adaptive control strategy for inertia damping of virtual synchronous generator Figure 1 ;

[0025] Figure 2 The process of adaptive control strategy for inertia damping of virtual synchronous generator Figure 2 ;

[0026] Figure 3 The basic principle and main circuit topology diagram of the virtual synchronous generator;

[0027] Figure 4 The active power output curve (left) and angular frequency change curve (right) compared with the traditional control method. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings, but the present invention can be implemented in different forms and is not limited to the embodiments described in the text. On the contrary, these embodiments are provided to make the content disclosed in the present invention more thorough and comprehensive.

[0029] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0031] Example 1, please refer to the attached Figure 1-4 , a virtual synchronous generator inertia damping adaptive control method, through the control technology to let the inverter simulate the damping and rotational inertia of the synchronous generator, so that the new energy power generation can be connected to the grid in the form of a synchronous generator, thereby improving the stability of the power grid. The present invention provides a virtual synchronous generator inertia damping adaptive control method, VSG technology can simulate the dynamic characteristics of traditional synchronous generators, including inertia response and primary frequency modulation functions, thereby providing the necessary active and reactive support for the power grid. This technology is crucial to maintaining the stability and reliability of the power grid, especially in the context of increasing penetration of renewable energy. Renewable energy grid-connected equipment, such as wind power generation and photovoltaic power generation, is usually connected to the grid through power electronic inverters. These devices themselves do not have the inertia and damping characteristics of traditional synchronous generators.

[0032] The research method of the virtual synchronous generator inertia damping adaptive control is as follows:

[0033] Step 1: Establish VSG control model

[0034] According to the mathematical model of the inverter, the equivalent circuit model of VSG is constructed; the control strategy of VSG is designed, involving the control design of the active-frequency, reactive-voltage power outer loops and the voltage-current dual closed-loop inner loop.

[0035] Step 2: Analyze the dynamic characteristics of the system

[0036] Through small signal modeling and analysis methods, the mutual constraints and contradictions between the dynamic regulation characteristics and static indicators of VSG are studied. This includes analyzing the influence of VSG's inertia and damping parameters on the dynamic and static characteristics of the system.

[0037] Step 3: Adaptive control strategy design

[0038] Based on the analysis of the system's dynamic characteristics, an adaptive control strategy is designed to improve the system's frequency response characteristics and output active power response characteristics, shorten the system's transient process, and improve system stability.

[0039] Step 4: Simulation Verification

[0040] The simulation model of VSG control strategy is built by MATLAB / Simulink simulation software to verify the effectiveness of the proposed control strategy. The simulation includes the test of dynamic response, stability and anti-interference ability of the system under different working conditions.

[0041] It should be noted that in this embodiment, the dynamic behavior of the synchronous generator, including its inertia and damping characteristics, can be accurately simulated. This method predicts and evaluates the performance of the VSG under different working conditions by establishing a mathematical model of the inverter and analyzing its dynamic response in the power system. It can reveal the impact of system parameter changes on the control performance of the VSG and provide a theoretical basis for the optimization of the control strategy. In addition, small signal analysis can also evaluate the stability of the VSG in the power system, including low-frequency oscillations and damping characteristics, which is crucial for the design and optimization of VSG control parameters.

[0042] Furthermore, the virtual inertia and damping coefficient can be dynamically adjusted to simulate the inertia and damping response of a traditional synchronous generator. This control strategy automatically adjusts the control parameters to maintain system stability and improve anti-interference capabilities by real-time monitoring of system status, such as frequency changes and power fluctuations. It can improve the dynamic frequency response characteristics of the system, enhance the anti-interference capability of the microgrid, and provide necessary synchronization support when the system is disturbed. In addition, the adaptive control strategy also takes into account the fast adjustment characteristics of the power electronic converter, so that it can maintain optimized performance under different operating conditions.

[0043] Furthermore, the simulation is related to inverter grid connection;

[0044] For details, please refer to the attached Figure 1 , in the inertia damping adaptive control strategy of the virtual synchronous generator (VSG), the system first initializes the parameters and collects the grid status in real time, including the frequency deviation and the frequency change rate. Based on the evaluation of the grid status, the system decides whether it is necessary to increase the virtual inertia or damping coefficient to adapt to the dynamic changes of the grid. If the grid status is unstable, the system will further determine whether the parameters need to be adjusted. Specifically, if the frequency deviation or the change rate still exceeds the preset threshold, the system will adjust the virtual inertia or damping coefficient accordingly. If the grid status is stable, the system will maintain the current parameters. This adaptive process is cyclic until the system determines that the grid status is stable and no further adjustment is required, at which point the process ends;

[0045] Furthermore, the flowchart of the VSG control system outlines a highly integrated and automated control strategy designed to simulate the dynamic characteristics of traditional synchronous generators to enhance grid stability. The process starts with real-time monitoring of grid parameters, such as frequency and voltage, which are the basis for the control system to make adjustment decisions. By identifying the current operating state, the system can determine whether frequency regulation is required and then determine the steady-state values ​​of virtual inertia and damping coefficient, which are crucial for simulating the response of synchronous generators.

[0046] With the judgment of the frequency modulation stage, the control system enters the adaptive mode and dynamically adjusts the control parameters of the VSG to respond to the frequency changes of the power grid. This process involves accurate PWM signal generation and dual closed-loop control of voltage and current to ensure that the output of the VSG is consistent with the control target while maintaining voltage stability and power factor correction. The entire process is a closed-loop system. After the frequency modulation control is executed, the system will monitor the power grid frequency again to confirm whether further adjustment is needed.

[0047] Through this comprehensive control strategy, the VSG control system can quickly respond to changes in the power grid and provide the necessary active and reactive power support. This not only improves the stability and reliability of the power grid, but also optimizes the power quality and reduces voltage fluctuations and harmonic content. This closed-loop control strategy enables the VSG control system to adapt to changing grid conditions and provides strong support for the stable operation of the power grid;

[0048] Furthermore, the working principle of VSG is to embed the mathematical model of the synchronous generator in the control system of the inverter, including simulating the rotational inertia and damping characteristics of the synchronous generator. VSG is able to simulate the primary frequency and voltage regulation characteristics of the synchronous generator, thereby achieving inertial support and frequency regulation for the power grid. The control strategies of VSG include active and reactive power control, voltage and frequency control, and droop control. The main circuit topology of VSG includes a DC power supply, a power electronic converter, and an output LC filter. The DC power supply can be regarded as a prime mover, the power electronic converter is responsible for converting DC power into AC power synchronized with the power grid, and the LC filter is used to smooth the output current waveform and reduce harmonics. The main circuit of VSG, combined with the control system, can achieve external characteristics similar to those of a traditional synchronous generator;

[0049] Furthermore, from the simulation comparison data, it can be seen that the output active power curve using adaptive control is smoother than the output active power curve using traditional VSG constant inertia damping control, especially when the given active power of the system changes. When adaptive control is used, the active power curve responds faster, the time to enter steady state is shorter, and the overshoot is small. This series shows that the system using the inertia damping adaptive control strategy can play a certain inhibitory role in the change of the system output when the given parameters change. Similarly, observing the change of angular frequency, when the system adopts the traditional constant inertia damping control strategy, the angular frequency offset is about 2rad / s at 0.4 seconds; when the inertia and damping adaptive control strategy is adopted, the angular frequency offset is about 0.8rad / s. The comparative test shows that the damping adaptive control strategy plays a certain role in restricting the angular frequency offset.

[0050] The system composition of the virtual synchronous generator (VSG) mainly includes two parts: the main circuit and the control system. The main circuit usually includes a DC voltage source, a DC / AC converter and a filter circuit, which is equivalent to the electromechanical energy conversion part of the synchronous generator. The control system is the core of the VSG to realize its functions, mainly including the VSG model itself and the control algorithm. The VSG model simulates the electromagnetic relationship and mechanical movement of the synchronous generator from the mechanism, while the control algorithm simulates the characteristics of the synchronous generator such as active frequency regulation and reactive voltage regulation from the external characteristics.

[0051] In terms of control strategy, VSG achieves rapid response and support to the grid voltage and frequency by simulating the primary frequency and voltage regulation functions of synchronous generators. This includes virtual inertia control, which provides inertial response to the grid by simulating the rotational inertia of traditional generators and enhances the dynamic stability of the system; damping control provides the necessary damping to suppress the power oscillation and frequency deviation of the system. The control strategy also includes active-frequency control and reactive-voltage control, which adjust the active power output and reactive power output of the VSG respectively in response to the frequency and voltage changes of the grid. In addition, the adaptive control strategy can dynamically adjust the control parameters according to the real-time conditions of the grid to optimize the performance of the VSG.

[0052] Example 2

[0053] Embodiment 2 of the present invention provides a virtual synchronous generator inertia damping adaptive control strategy, which is described in detail as follows:

[0054] Inertia control, when the grid is disturbed, such as sudden load changes or fluctuations in renewable energy output, VSG provides additional inertia support by increasing its inertia to reduce system frequency fluctuations. This inertia control is usually related to the grid's angular frequency deviation and its rate of change, and the inertia size is adjusted through an adaptive algorithm to maintain system stability.

[0055] Damping control, the role of damping control is to suppress oscillations and power fluctuations in the power grid. The damping coefficient of the VSG is adjusted according to the dynamic response of the system to optimize the damping characteristics of the system. This adaptive damping control helps to reduce the power oscillation of the system and improve the dynamic stability of the system.

[0056] Adaptive control, the adaptive control algorithm can dynamically adjust the inertia and damping parameters according to the real-time status of the system. The control parameters of the VSG are dynamically adjusted according to the real-time frequency deviation and power change rate of the power grid to achieve more refined and flexible control.

[0057] Example 3

[0058] Figure 3 It is a comparison between the traditional control method and the adaptive control method. Compared with the traditional control method, the adaptive control has a faster dynamic response speed of active output and a smaller change in angular frequency.

[0059] The above is an exemplary description of the present invention in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A virtual synchronous generator inertia damping adaptive control method, characterized in that: The following steps are involved: Step 1: Initialize parameters and collect grid status in real time through the VSG control system; Step 2: Based on the evaluation of the grid status, the VSG control system decides whether it is necessary to increase the virtual inertia or damping coefficient to adapt to the dynamic changes of the grid; Step 3: The VSG control system further determines whether parameters need to be adjusted based on whether the power grid state is stable; In step three, the VSG control system adjusts the virtual inertia or damping coefficient accordingly according to whether the frequency deviation or change rate still exceeds the preset threshold. If the grid state is stable, the system will maintain the current parameters. This adaptive process is cyclic until the system determines that the grid state is stable and no further adjustment is required, at which point the process ends.

2. A virtual synchronous generator inertia damping adaptive control method according to claim 1, characterized in that: In the step 1, the grid status collected in real time by the VSG control system includes frequency deviation and frequency change rate.

3. A virtual synchronous generator inertia damping adaptive control method according to claim 1, characterized in that: The VSG control system monitors grid parameters in real time, including frequency and voltage. By identifying the current operating status, the VSG control system can determine whether frequency modulation operation is required and then determine the steady-state values ​​of the virtual inertia and damping coefficient.

4. A virtual synchronous generator inertia damping adaptive control method according to claim 1, characterized in that: As the frequency regulation phase is determined, the VSG control system enters the adaptive mode and dynamically adjusts the control parameters of the VSG to respond to the frequency changes of the power grid.

5. A virtual synchronous generator inertia damping adaptive control method according to claim 4, characterized in that: The VSG control system enters the adaptive mode as the frequency modulation stage is judged. The process of dynamically adjusting the control parameters of the VSG to respond to the frequency changes of the power grid involves precise PWM signal generation and dual closed-loop control of voltage and current. It is necessary to ensure that the output of the VSG is consistent with the control target while maintaining voltage stability and power factor correction.

6. A virtual synchronous generator inertia damping adaptive control method according to claim 4, characterized in that: As the VSG control system judges the frequency modulation stage, the control system enters the adaptive mode and dynamically adjusts the control parameters of the VSG to respond to the frequency changes of the power grid. This process is a closed-loop system. After the frequency modulation control is executed, the system will monitor the power grid frequency again to confirm whether further adjustment is needed.

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